Systematic adsorption process of petroleum hydrocarbon by immobilised petroleum-degradation bacteria system in degradation pathways

In order to effectively control petroleum hydrocarbon pollution by immobilisation technology,it is necessary to understanding the degradation pathways of petroleum hydrocarbon in immobilised petroleum-degradation bacteria system.However,the adsorption in degradation process is rarely studied.In this study,adsorption process of petroleum hydrocarbon was synergistically studied by means of the surface properties,adsorption thermodynamics and molecular simulation.The results indicate that the immobilised petroleum-degradation bacteria have many holes for the bacteria to adsorb.The diesel adsorption by immobilised petroleum-degradation bacteria is a spontaneous,entropy-increasing and endothermic process.Diesel is first adsorbed to the surface of immobilised petroleum-degradation bacteria through hydrogen bonding,and then is biodegraded.This study provided substantial knowledge of immobilised technology in controlling petroleum hydrocarbon pollution.

Soil Quality Evaluation of Hydrocarbon Polluted Parcels

For hydrocarbon polluted soils that underwent bioremediation it is important to assess its condition after a period of time, but it is more useful when there is an opportunity of comparison against an unpolluted soil and an untreated polluted one. This paper provides a comparison of three adjacent parcels, being the first clean, the second polluted and bioremediated, the third polluted and left to natural attenuation. Study was conducted determining pH, electrical conductivity, carbonates, soil organic matter, chemical oxygen demand, eight anions, and twelve metals. Data were compared against those references for agricultural soils found in the Mexican NOM-021. A Pearson correlation was applied to find coincidences between the three parcels, obtained results allowed to say that bioremediated parcel allowed for most uniform pH, negligible salinity risk, and medium content of soil organic matter, but treatment has enabled heavy metal accumulation since its values are higher in respect to the other parcels. Natural attenuated parcel has some spots with lower pH, a moderately saline risk, a high content of soil organic matter, and lower content of heavy metals. The clean or unaffected parcel exhibit the higher pH values, a slightly saline condition, soil organic matter ranges from high to very high content, heavy metals content is medium, but no reaching dangerous levels. An important assessment is that bioremediation has enhanced the bioavailability of soil organic matter but it is not similar to the values in the unpolluted parcel.

Molecular distribution and seasonal variation of hydrocarbons in PM_(2.5) from Beijing during 2006

Normal （n）-alkanes and polycyclic aromatic hydrocarbons （PAHs） in PM2.5 were collected from Beijing in 2006 and analyzed using a thermal desorption-GC/MS technique. Annual average concentrations of n-alkanes and PAHs were 282 ±96 and 125 ± 150ng/m^3, respectively： both were highest in winter and lowest in summer. C19-C25 compounds dominated the n-alkanes while benzo[b]fluoranthene, benzo[e]pyrene, and phenanthrene were the most abundant PAHs. The n-alkanes exhibited moderate correlations with organic carbon （OC） and elemental carbon （EC） throughout the year, but the relation- ships between the PAHs, OC and EC differed between the heating and non-heating seasons. The health risks associated with PAHs in winter were more than 40 times those in spring and summer even though the PM2.5 loadings were comparable. Carbon preference index values （〈1.5） indicated that the n-alkanes were mostly from fossil fuel combustion. The ratios of indeno[123-cd]pyrene to benzo[ghi]pyrelene in summer and spring were 0.58 ± 0.12 and 0.63 ± 0.09, respectively, suggesting that the PAHs mainly originated from motor vehicles, but higher ratios in winter reflected an increased infuence from coal, which is extensively burned for domestic heating. A comprehensive comparison showed that PAH pollution in Beijing has decreased in the past 10 years.